About one in five U.S. adult cigarette smokers have tried an electronic cigarette.

In 2011, about 21% of adults who smoke traditional cigarettes had used electronic cigarettes, also known as e-cigarettes, up from about 10% in 2010, according to a study released today by the Centers for Disease Control and Prevention.

Overall, about 6% of all adults have tried e-cigarettes, with estimates nearly doubling from 2010.  This study is the first to report changes in awareness and use of e-cigarettes between 2010 and 2011.

During 2010–2011, adults who have used e-cigarettes increased among both sexes, non-Hispanic Whites, those aged 45–54 years, those living in the South, and current and former smokers and current and former smokers.  In both 2010 and 2011, e-cigarette use was significantly higher among current smokers compared to both former and never smokers.  Awareness of e-cigarettes rose from about four in 10 adults in 2010 to six in 10 adults in 2011.

“E-cigarette use is growing rapidly,” said CDC Director Tom Frieden, MD, MPH. “There is still a lot we don’t know about these products, including whether they will decrease or increase use of traditional cigarettes.”

Although e-cigarettes appear to have far fewer of the toxins found in smoke compared to traditional cigarettes, the impact of e-cigarettes on long-term health must be studied.  Research is needed to assess how e-cigarette marketing could impact initiation and use of traditional cigarettes, particularly among young people.

“If large numbers of adult smokers become users of both traditional cigarettes and e-cigarettes—rather than using e-cigarettes to quit cigarettes completely—the net public health effect could be quite negative,” said Tim McAfee, MD MPH, director of the Office on Smoking and Health at CDC.